| Message ID | 20220519155925.1.Iedc61f9ef220a89af6a031200a7850a27a440134@changeid (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/2] dt-bindings: HID: i2c-hid: elan: Introduce bindings for Elan eKTH6915 | expand |
On Thu, May 19, 2022 at 04:00:02PM -0700, Douglas Anderson wrote: > Like many i2c-hid touchscreen controllers, the Elan eKTH6915 > controller has a reset gpio. For the Goodix GT7375P touchscreen the > decision was to add a new binding rather than trying to add a new GPIO > to the existing i2c-hid binding. We'll follow the lead and do it here, > too. > > SIDE NOTE: the Elan eKTH6915 is a touchscreen _controller_ that's > included as a part on some touchscreens. The reset line isn't truly > necessary for the functioning of the touchscreen, so it's possible > that some designs won't have it hooked up and will just guarantee the > power sequencing requirements with RLC circuits. Thus, we'll mark the > reset gpio as optional. > > Note that if the reset GPIO isn't used there's actually no true need > to use the "elan,ekth6915" compatible instead of the "hid-over-i2c" on > Linux. However: > - Officially using just "hid-over-i2c" for this device violates the > existing "hid-over-i2c" bindings. The bindings say that you're not > supposed to use "post-power-on-delay-ms" without specifying a more > specific compatible. Currently the Linux driver doesn't enforce > this, but it violates the bindings to just use > "hid-over-i2c". ...and if you're going to add a more specific > compatible anyway, might as well do it right. > - Using this compatible means we don't need to specify > "hid-descr-addr" since it's inferred from the compatible. > - Using this compatible means that the regulator names match the names > on the Elan datasheet (vcc33 / vccio) vs the generic hid-over-i2c > (vdd / vddl). > > Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Thanks.
diff --git a/Documentation/devicetree/bindings/input/elan,ekth6915.yaml b/Documentation/devicetree/bindings/input/elan,ekth6915.yaml new file mode 100644 index 000000000000..05e6f2df604c --- /dev/null +++ b/Documentation/devicetree/bindings/input/elan,ekth6915.yaml @@ -0,0 +1,65 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/input/elan,ekth6915.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Elan eKTH6915 touchscreen controller + +maintainers: + - Douglas Anderson <dianders@chromium.org> + +description: + Supports the Elan eKTH6915 touchscreen controller. + This touchscreen controller uses the i2c-hid protocol with a reset GPIO. + +properties: + compatible: + items: + - const: elan,ekth6915 + + reg: + const: 0x10 + + interrupts: + maxItems: 1 + + reset-gpios: + description: Reset GPIO; not all touchscreens using eKTH6915 hook this up. + + vcc33-supply: + description: The 3.3V supply to the touchscreen. + + vccio-supply: + description: + The IO supply to the touchscreen. Need not be specified if this is the + same as the 3.3V supply. + +required: + - compatible + - reg + - interrupts + - vcc33-supply + +additionalProperties: false + +examples: + - | + #include <dt-bindings/gpio/gpio.h> + #include <dt-bindings/interrupt-controller/irq.h> + + i2c { + #address-cells = <1>; + #size-cells = <0>; + + ap_ts: touchscreen@10 { + compatible = "elan,ekth6915"; + reg = <0x10>; + + interrupt-parent = <&tlmm>; + interrupts = <9 IRQ_TYPE_LEVEL_LOW>; + + reset-gpios = <&tlmm 8 GPIO_ACTIVE_LOW>; + vcc33-supply = <&pp3300_ts>; + }; + };
Like many i2c-hid touchscreen controllers, the Elan eKTH6915 controller has a reset gpio. For the Goodix GT7375P touchscreen the decision was to add a new binding rather than trying to add a new GPIO to the existing i2c-hid binding. We'll follow the lead and do it here, too. SIDE NOTE: the Elan eKTH6915 is a touchscreen _controller_ that's included as a part on some touchscreens. The reset line isn't truly necessary for the functioning of the touchscreen, so it's possible that some designs won't have it hooked up and will just guarantee the power sequencing requirements with RLC circuits. Thus, we'll mark the reset gpio as optional. Note that if the reset GPIO isn't used there's actually no true need to use the "elan,ekth6915" compatible instead of the "hid-over-i2c" on Linux. However: - Officially using just "hid-over-i2c" for this device violates the existing "hid-over-i2c" bindings. The bindings say that you're not supposed to use "post-power-on-delay-ms" without specifying a more specific compatible. Currently the Linux driver doesn't enforce this, but it violates the bindings to just use "hid-over-i2c". ...and if you're going to add a more specific compatible anyway, might as well do it right. - Using this compatible means we don't need to specify "hid-descr-addr" since it's inferred from the compatible. - Using this compatible means that the regulator names match the names on the Elan datasheet (vcc33 / vccio) vs the generic hid-over-i2c (vdd / vddl). Signed-off-by: Douglas Anderson <dianders@chromium.org> --- .../bindings/input/elan,ekth6915.yaml | 65 +++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/devicetree/bindings/input/elan,ekth6915.yaml